Types of infections
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When you listen to the news, you hear about many different forms of
electronic infection. The most common are:
File Viruses - A small piece of software that piggybacks on real programs. For example, it might attach itself to a program such as a spreadsheet program. Each time the spreadsheet program runs, the virus runs, too, and it has the chance to reproduce (by attaching to other programs) or wreak havoc. Boot Sector Virus - Program placed in the computer's boot sector. Because the computer loads boot sector information into memory, the virus loads into RAM at the same time. Macro Virus - Written in a specific language and attaches itself to a document created in a specific application such as Excel or Word. Once the document (along with the virus) is opened and loaded into memory, the virus can attach itself to other documents. E-mail viruses - An e-mail virus moves around in e-mail messages, and usually replicates itself by automatically mailing itself to dozens of people in the victim's e-mail address book. Worm virus- A worm is a small piece of software that uses computer networks and security holes to replicate itself. A copy of the worm scans the network for another machine that has a specific security hole. It copies itself to the new machine using the security hole, and then starts replicating from there, as well. Trojan horses- A Trojan horse is simply a computer program. The program claims to do one thing (it may claim to be a game) but instead does damage when you run it (it may erase your hard disk). Trojan horses have no way to replicate automatically. Stealth virus - A program written to avoid anti-virus software detection. When the anti-virus program executes, the stealth virus provides the anti-virus software with a fake image. Polymorphic virus - Constantly changes in order to avoid detection by an anti-virus program. Hoax virus - These are false reports about non-existent viruses, often claiming to do impossible things. Unfortunately some recipients occasionally believe a hoax to be a true virus warning and may take drastic action (such as shutting down their network). Src: http://computer.howstuffworks.com/virus.htm |